U.S. patent number 9,748,105 [Application Number 14/337,908] was granted by the patent office on 2017-08-29 for tungsten deposition with tungsten hexafluoride (wf6) etchback.
This patent grant is currently assigned to APPLIED MATERIALS, INC.. The grantee listed for this patent is Applied Materials, Inc.. Invention is credited to Kai Wu, Sang Ho Yu.
United States Patent |
9,748,105 |
Wu , et al. |
August 29, 2017 |
Tungsten deposition with tungsten hexafluoride (WF6) etchback
Abstract
Implementations described herein generally relate to methods for
forming tungsten materials on substrates using vapor deposition
processes. The method comprises positioning a substrate having a
feature formed therein in a substrate processing chamber,
depositing a first film of a bulk tungsten layer by introducing a
continuous flow of a hydrogen containing gas and a tungsten halide
compound to the processing chamber to deposit the first tungsten
film over the feature, etching the first film of the bulk tungsten
layer using a plasma treatment to remove a portion of the first
film by exposing the first film to a continuous flow of the
tungsten halide compound and an activated treatment gas and
depositing a second film of the bulk tungsten layer by introducing
a continuous flow of the hydrogen containing gas and the tungsten
halide compound to the processing chamber to deposit the second
tungsten film over the first tungsten film.
Inventors: |
Wu; Kai (Palo Alto, CA), Yu;
Sang Ho (Cupertino, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
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Assignee: |
APPLIED MATERIALS, INC. (Santa
Clara, CA)
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Family
ID: |
52467136 |
Appl.
No.: |
14/337,908 |
Filed: |
July 22, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150050807 A1 |
Feb 19, 2015 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61866665 |
Aug 16, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
21/28556 (20130101); C23C 16/14 (20130101); H01L
21/76877 (20130101); C23C 16/045 (20130101); H01L
21/32136 (20130101) |
Current International
Class: |
H01L
21/285 (20060101); H01L 21/768 (20060101); H01L
21/321 (20060101); C23C 16/14 (20060101); C23C
16/04 (20060101); H01L 21/3213 (20060101) |
Field of
Search: |
;438/627-629,672,679,685 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-2004-0087406 |
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Oct 2004 |
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KR |
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Other References
International Search Report and Written Opinion for International
Application No. PCT/US2014/047618 dated Nov. 5, 2014. cited by
applicant.
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Primary Examiner: Pham; Thanhha
Attorney, Agent or Firm: Patterson + Sheridan LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims benefit of U.S. provisional patent
application Ser. No. 61/866,665, filed Aug. 16, 2013. The
aforementioned related patent application is herein incorporated by
reference in its entirety.
Claims
The invention claimed is:
1. A method for depositing a tungsten film on a substrate,
comprising: positioning a substrate having a feature formed therein
in a substrate processing chamber, wherein the feature is defined
by at least one sidewall and a bottom surface; depositing a first
tungsten film of a bulk tungsten layer by introducing a continuous
flow of a hydrogen containing gas and a tungsten halide compound to
the processing chamber to deposit the first tungsten film over the
feature while maintaining the processing chamber at a first
pressure and a first temperature of between about 300 degrees
Celsius and about 430 degrees Celsius; etching the first tungsten
film of the bulk tungsten layer in the processing chamber using a
plasma treatment to remove a portion of the first tungsten film by
exposing the first tungsten film to a continuous flow of the
tungsten halide compound and an activated treatment gas while
maintaining the processing chamber at a second pressure less than
the first pressure and a second temperature of between about 300
degrees Celsius and about 430 degrees Celsius, wherein the
activated treatment gas comprises activated helium gas, activated
argon gas, activated oxygen gas, or activated nitrogen gas; and
depositing a second tungsten film of the bulk tungsten layer by
introducing a continuous flow of the hydrogen containing gas and
the tungsten halide compound to the processing chamber to deposit
the second tungsten film over the first tungsten film.
2. The method of claim 1, wherein the tungsten halide compound is
selected from the group consisting of: tungsten hexafluoride
(WF.sub.6) and tungsten hexachloride (WCl.sub.6).
3. The method of claim 2, wherein the hydrogen containing gas is
hydrogen (H.sub.2).
4. The method of claim 3, wherein the activated treatment gas is
activated argon gas.
5. The method of claim 4, wherein the activated treatment gas is
formed in-situ in the substrate processing chamber.
6. The method of claim 4, wherein the activated treatment gas is
formed using a remote plasma source.
7. The method of claim 6, wherein the feature is formed in and
below a surface of a dielectric layer formed on the substrate.
8. The method of claim 1, wherein an adhesion layer is formed over
the at least one sidewall and the bottom surface of the
feature.
9. The method of claim 8, wherein a nucleation layer is formed over
the adhesion layer.
10. The method of claim 1, wherein the first tungsten film and the
second tungsten film are deposited using a thermal chemical vapor
deposition (CVD) process.
11. The method of claim 1, wherein a nominal minimal dimension
across a gap in the surface of the substrate created by the feature
is 32 nm or less.
12. The method of claim 1, wherein the feature is a high aspect
ratio feature selected from the group consisting of a contact, a
via, a trench and a line.
13. A method for depositing a tungsten film on a substrate,
comprising: positioning a substrate having a feature formed therein
in a substrate processing chamber, wherein the feature is defined
by at least one sidewall and a bottom surface; depositing a first
tungsten film of a bulk tungsten layer by introducing a continuous
flow of a hydrogen containing gas and a tungsten halide compound to
the processing chamber to deposit the first tungsten film over the
feature while maintaining the processing chamber at a first
pressure and a first temperature of between about 300 degrees
Celsius and about 430 degrees Celsius; etching the first tungsten
film of the bulk tungsten layer in the processing chamber using a
plasma treatment to remove a portion of the first tungsten film by
exposing the first tungsten film to a continuous flow of the
tungsten halide compound and an activated treatment gas while
maintaining the processing chamber at a second pressure less than
the first pressure and a second temperature of between about 300
degrees Celsius and about 430 degrees Celsius, wherein the
activated treatment gas comprises activated helium gas, activated
argon gas, activated oxygen gas, or activated nitrogen gas; and
depositing a second tungsten film of the bulk tungsten layer by
introducing a continuous flow of the hydrogen containing gas and
the tungsten halide compound to the processing chamber to deposit
the second tungsten film over the first tungsten film, wherein the
portion of the first tungsten film is removed at an etch rate in a
range from about 0.5 .ANG./second and about 3 .ANG./second.
14. The method of claim 13, wherein the tungsten halide compound is
selected from the group consisting of: tungsten hexafluoride
(WF.sub.6) and tungsten hexachloride (WCl.sub.6).
15. The method of claim 14, wherein the hydrogen containing gas is
hydrogen (H.sub.2).
16. The method of claim 15, wherein the activated treatment gas is
activated argon gas.
17. The method of claim 16, wherein the activated treatment gas is
formed in-situ in the substrate processing chamber.
18. The method of claim 17, wherein the activated treatment gas is
formed using a remote plasma source.
19. The method of claim 13, wherein the feature is formed in and
below a surface of a dielectric layer formed on the substrate.
Description
BACKGROUND
Field
Implementations described herein generally relate to the processing
of substrates, and more particularly relate to methods for forming
tungsten materials on substrates using vapor deposition
processes.
Description of the Related Art
Reliably producing nanometer-sized features is one of the key
technologies for the next generation of semiconductor devices. The
shrinking dimensions of circuits and devices have placed additional
demands on processing capabilities. The multilevel interconnects
that lie at the heart of integrated circuit technology require
precise processing of high aspect ratio features, such as vies and
other interconnects. Reliable formation of these interconnects is
very important to future success and to the continued effort to
increase circuit density and quality of individual substrates.
Metallization of features formed on substrates includes CVD
deposition of metals such as tungsten. Tungsten can be used for
metal fill of source contacts, drain contacts, metal gate fill and
gate contacts as well as applications in DRAM and flash memory.
With technology node shrinkage, tungsten films having low
resistivity and low roughness are desirable for device
characteristics and for integration with subsequent processes.
Chemical vapor deposition (CVD) is one process technology used for
metal fill of tungsten. A pattern is etched in the underlying
interlayer dielectric (ILD) material 10. Tungsten is then processed
to fill the etched substrates.
But successive reduction in feature sizes has meant that there is
increasing difficulty in this process. When the tungsten layer is
formed on the sidewalls as well as the bottom surface of the
feature, the CVD process deposits the metal on both surfaces within
the feature. With high aspect ratio features, as can be seen in Hal
which shows the result of tungsten deposition growth during CVD,
the opening (in new generation devices--where the nominal feature
gap opening dimensions are in the range of 32 nm and less--(gap in
the surface of the dielectric material layer created by the feature
(or depression) therein can be 32 nm or less)) of the feature can
become "closed off" 27 before the bottom up fill process reaches
the full height of the thickness of the dielectric layer to fully
fill the feature with substantially void-free tungsten fill
material. The tungsten growth on the sidewalls tends to close off
the feature at the feature opening before the lower portion of the
feature has completely grown from the feature bottom surface
resulting in a void 30 forming within the feature. The presence of
the void 30 changes the material and operating characteristics of
the interconnect feature and may eventually cause improper
operation and premature breakdown of the device. The conductive
element, line, to be efficient, carries near its practical maximum
current density as established and known by persons skilled in the
art in current state of the art devices. The goal is to achieve the
same current flow density or higher in smaller features in future
devices.
Therefore, it is desirable to use CVD for void-free filling of high
aspect ratio ultra-small features with tungsten without the
problems and limitations of conventional techniques discussed
above.
SUMMARY
Implementations described herein generally relate to the processing
of substrates, and more particularly relate to methods for forming
tungsten materials on substrates using vapor deposition processes.
In one implementation a method for depositing a tungsten film on a
substrate is provided. The method comprises positioning a substrate
having a feature formed therein in a substrate processing chamber,
wherein the feature is defined by at least one sidewall and a
bottom surface, depositing a first film of a bulk tungsten layer by
introducing a continuous flow of a hydrogen containing gas and a
tungsten halide compound to the processing chamber to deposit the
first tungsten film over the feature, etching the first film of the
bulk tungsten layer using a plasma treatment to remove a portion of
the first film by exposing the first film to a continuous flow of
the tungsten halide compound and an activated treatment gas and
depositing a second film of the bulk tungsten layer by introducing
a continuous flow of the hydrogen containing gas and the tungsten
halide compound to the processing chamber to deposit the second
tungsten film over the first tungsten film.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the
present disclosure can be understood in detail, a more particular
description of the disclosure, briefly summarized above, may be had
by reference to implementations, some of which are illustrated in
the appended drawings. It is to be noted, however, that the
appended drawings illustrate only typical implementations of this
disclosure and are therefore not to be considered limiting of its
scope, for the disclosure may admit to other equally effective
implementations.
FIG. 1 (Prior Art) is a schematic cross-sectional views of a
substrate with a feature having tungsten deposited therein using
prior art processes;
FIG. 2 is a schematic cross-sectional view of a plasma enhanced CVD
(PECVD) processing chamber that may be used for depositing a
tungsten layer according to implementations described herein;
FIG. 3 is a flow diagram depicting a method for depositing a
tungsten fill layer according to implementations described
herein;
FIGS. 4A-4F are schematic cross-sectional views of a substrate with
a feature having tungsten deposited therein according to
implementations described herein; and
FIG. 5 is a schematic plan view of a duster tool that may be used
for performing the implementations described herein.
To facilitate understanding, identical reference numerals have been
used, where possible, to designate identical elements that are
common to the figures. It is contemplated that elements disclosed
in one implementation may be beneficially utilized on other
implementations without specific recitation.
DETAILED DESCRIPTION
Implementations described herein generally relate to the processing
of substrates, and more particularly relate to methods for forming
tungsten materials on substrates using vapor deposition
processes.
Tungsten (W) has been used at contact level in logic application
for about two decades. In recent advanced CMOS devices, new
technology such as metal gate and FinFET emerge, which leads to a
new application for tungsten as metal gate fill for both PMOS and
NMOS devices. In 3D NAND devices, tungsten is also used for metal
gate fill. The requirements for tungsten fill become more and more
challenging. For contact, the overhang becomes more challenging as
the dimensions of contacts are getting smaller and typically leaves
a big seam after tungsten conformal fill. Furthermore, the seam
will be exposed to slurry during WCMP, which causes integration
issues. For metal gate trench in both advanced CMOS and 3D NAND,
traditional tungsten conformal growth inevitably leaves a seam in
the middle, which might be expanded wider during tungsten etch back
process, causing device failure. Therefore, a seamless tungsten
fill is desired for both contact and metal gate fill in the
advanced logic and memory devices. This seamless tungsten fill can
be achieved by tungsten deposition-etchback-deposition fill
processes described herein. Normally tungsten etchback processes
utilize NF.sub.3 as the etchant in a dedicated etch chamber for
better process control. The additional etch chamber makes tool
configuration more complicated. Another major drawback of NF.sub.3
etch is that NF.sub.3 will poison the tungsten surface after
etchback so that the second tungsten deposition process requires
another tungsten nucleation layer leading to lower throughput and
higher contact/line resistance.
In certain implementations described herein, tungsten etchback is
achieved by using tungsten halide plasma (e.g., WF.sub.6 plasma).
The plasma source can be RF or a remote plasma source (RPS). Atomic
fluorine is dissociated from WF.sub.6 plasma and is used to etch
metal tungsten. The etch rate is dependent on WF.sub.6 flow and
plasma condition. By adjusting the process conditions, a very mild
etch rate in the range of .about.0.5 .ANG./second to 3 .ANG./second
can be achieved to control the etchback amount. With that, seamless
fill can be produced on structures with different critical
dimensions (CD) and overhang, and TiN liner attack by atomic
fluorine can be avoided. Since there is no nitrogen in the etchant,
there is no poisoning effect after WF.sub.6 etchback. The second
deposition process can utilize WF.sub.6+H.sub.2 chemistry directly
without the need for a nucleation layer. Another big advantage is a
single chamber deposition-etch-deposition process can be achieved
since WF.sub.6 may be used as both deposition precursor and etchant
in one chamber. A standard WCVD chamber with RF or RPS plasma
capability can perform both deposition and etchback, which provides
improved throughput and chamber redundancy.
FIG. 2 is a schematic cross-sectional view of a PECVD processing
chamber 200 that may be used for depositing a tungsten layer
according to the implementations described herein. Such a
processing chamber 200 is available from Applied Materials, Inc.
located in Santa Clara, Calif., and a brief description thereof
follows. An integrated processing system capable of performing the
nucleation and bulk layer deposition methods described herein is
the tungsten chemical vapor deposition chamber, available from
Applied Materials, Inc. located in Santa Clara, Calif. It is to be
understood that the chamber described below is an exemplary
implementation and other chambers, including chambers from other
manufacturers may be used with or modified to match implementations
of this disclosure without diverging from the inventive
characteristics described herein.
The processing chamber 200 may be part of a processing system that
includes multiple processing chambers connected to a central
transfer chamber and serviced by a robot (see FIG. 5). The
processing chamber 200 includes walls 206, a bottom 208, and a lid
210 that define a processing volume 212. The walls 206 and bottom
208 are typically fabricated from a unitary block of aluminum. The
wads 206 may have conduits (not shown) therein through which a
fluid may be passed to control the temperature of the walls 206.
The processing chamber 200 may also include a pumping ring 214 that
couples the processing volume 212 to an exhaust port 216 as well as
other pumping components (not shown).
A substrate support assembly 238, which may be heated, may be
centrally disposed within the processing chamber 200. The substrate
support assembly 238 supports a substrate 203 during a deposition
process. The substrate support assembly 238 generally is fabricated
from aluminum, ceramic or a combination of aluminum and ceramic and
typically includes a vacuum port (not shown) and at least one or
more heating elements 232.
The vacuum port may be used to apply a vacuum between the substrate
203 and the substrate support assembly 238 to secure the substrate
203 to the substrate support assembly 238 during the deposition
process. The one or more heating elements 232 may be, for example,
electrodes disposed in the substrate support assembly 238, and
coupled to a power source 230, to heat the substrate support
assembly 238 and substrate 203 positioned thereon to a
predetermined temperature.
Generally, the substrate support assembly 238 is coupled to a stem
242. The stem 242 provides a conduit for electrical leads, vacuum
and gas supply lines between the substrate support assembly 238 and
other components of the processing chamber 200. Additionally, the
stem 242 couples the substrate support assembly 238 to a lift
system 244 that moves the substrate support assembly 238 between an
elevated position (as shown in FIG. 2) and a lowered position (not
shown). Bellows 246 provides a vacuum seal between the processing
volume 212 and the atmosphere outside the chamber 200 while
facilitating the movement of the substrate support assembly
238.
The substrate support assembly 238 additionally supports a
circumscribing shadow ring 248. The shadow ring 248 is annular in
form and typically comprises a ceramic material such as, for
example, aluminum nitride. Generally, the shadow ring 248 prevents
deposition at the edge of the substrate 203 and substrate support
assembly 238.
The lid 210 is supported by the walls 206 and may be removable to
allow for servicing of the processing chamber 200. The lid 210 may
generally be comprised of aluminum and may additionally have heat
transfer fluid channels 224 formed therein. The heat transfer fluid
channels 224 are coupled to a fluid source (not shown) that flows a
heat transfer fluid through the lid 210. Fluid flowing through the
heat transfer fluid channels 224 regulates the temperature of the
lid 210.
A showerhead 218 may generally be coupled to an interior side 220
of the lid 210. A perforated blocker plate 236 may optionally be
disposed in the space 222 between the showerhead 218 and lid 210.
Gases (i.e., process and other gases) that enter the processing
chamber 200 through the mixing block 234 are first diffused by the
blocker plate 236 as the gases fill the space 222 behind the
showerhead 218. The gases then pass through the showerhead 218 and
into the processing chamber 200. The blocker plate 236 and the
showerhead 218 are configured to provide a uniform flow of gases to
the processing chamber 200. Uniform gas flow is desirable to
promote uniform layer formation on the substrate 203.
A gas source 260 is coupled to the lid 210 to provide gas through
gas passages in the showerhead 218 to a processing area between the
showerhead 218 and the substrate 203. A vacuum pump (not shown) may
be coupled to the processing chamber 200 to control the processing
volume at a desired pressure. An RF source 270 is coupled through a
match network 290 to the lid 210 and/or to the showerhead 218 to
provide an RF current to the showerhead 218. The RF current creates
an electric field between the showerhead 218 and the substrate
support assembly 238 so that plasma may be generated from the gases
between the showerhead 218 and the substrate support assembly
238.
A remote plasma source 280, such as an inductively coupled remote
plasma source, may also be coupled between the gas source 260 and
the lid 210. Between processing substrates, a cleaning gas may be
provided to the remote plasma source 280 so that remote plasma is
generated. The radicals from the remote plasma may be provided to
the processing chamber for a plasma etching process. The etching
gas may be further excited by the RF source 270 provided to the
showerhead 218.
FIG. 3 is a flow diagram depicting a method 300 for depositing a
tungsten fill layer according to implementations described herein.
At block 310, a substrate having a feature formed therein is
positioned in a processing chamber. At block 320, a tungsten
nucleation layer is deposited in the feature. At block 330, a first
tungsten film is deposited over the tungsten nucleation layer using
a tungsten containing gas. At block 340, the first tungsten film is
etched using the tungsten containing gas to remove a portion of the
first tungsten film. At block 350, a second tungsten film is
deposited over the first tungsten film using the tungsten
containing gas. At block 360, it is determined whether the overall
desired thickness of the tungsten layer is deposited. If the
overall desired thickness has been achieved, the process ends. If
the overall desired thickness has not been achieved the
etch-deposition process may be repeated.
FIGS. 4A-4F are schematic cross-sectional views of a substrate at
lapsed process periods, such as blocks 310-360 of process 300,
according to implementations described herein. Process 300 is
utilized to form tungsten metallization materials on a substrate
surface. In one example, workpiece 400, depicted in FIGS. 4A-4F,
may be fabricated or otherwise formed by process 300.
FIG. 4A depicts workpiece 400 that contains a dielectric layer 410
disposed on a substrate 402 and a feature 408 formed or otherwise
contained within dielectric layer 410. The feature 408 has at least
one sidewall 422 and a bottom surface 424. Exemplary features
include features such as vias, trenches, lines, contact holes, or
other features utilized in a semiconductor, solar, or other
electronic devices, such as high aspect contact plugs. In some
implementations where the feature is a via, the via may have a high
aspect ratio (e.g., AR .about.20-50). Generally, substrate 402 is a
silicon substrate or at least contains silicon or a silicon-based
material. In many examples, workpiece 400 is a semiconductor
workpiece having a silicon substrate or wafer as substrate 402;
dielectric layer 410 contains at least one dielectric material,
such as silicon, monocrystalline silicon, microcrystalline silicon,
polycrystalline silicon (polysilicon), amorphous silicon,
hydrogenated amorphous silicon, silicon oxide materials, dopant
derivatives thereof, or combinations thereof.
Upper surface 404 of workpiece 400 may have at least one or more
contaminants disposed thereon. Contaminants disposed on upper
surface 404 of workpiece 400 may include native oxides, residues,
particles, and/or other contaminants. An optional process may be
utilized to clean upper surface 404 of workpiece 400, in various
implementations of process 300. For example, contaminants are
removed from upper surface 404 of workpiece 400 during an optional
process, such as a preclean process or a backside polishing
process. FIG. 4A depicts upper surface 404 of workpiece 400 free of
contaminants or substantially free of contaminants, including free
of native oxides.
In some implementations, upper surface 404 of workpiece 400 may be
exposed to a pre-clean process. Upper surface 404 usually contains
silicon, polysilicon, or silicon containing surface (e.g.,
silicide) disposed thereon and may be exposed to pre-clean
solution, vapor, or plasma during a pre-clean process. In one
implementation, upper surface 404 is exposed to a reducing agent in
gaseous form, such as silane, disilane, diborane, hydrogen,
phosphine, or derivatives thereof. A carrier gas may be co-flowed
with the reducing agent. Carrier gases include hydrogen, nitrogen,
argon, or combinations thereof. In another implementation, upper
surface 404 is exposed to a plasma pre-clean process. The plasma
may be generated internal (e.g., in situ plasma) or generated
externally (e.g., remote plasma system). Upper surface 404 may be
exposed to a plasma formed from a gas or a gaseous mixture
containing argon, helium, neon, hydrogen, nitrogen, ammonia,
silane, disilane, diborane, or mixtures thereof. In several
examples, the plasma may be formed from a hydrogen and ammonia
mixture, a hydrogen and nitrogen mixture, or a nitrogen and ammonia
mixture.
After the optional pre-clean process, an adhesion layer may be
formed on the dielectric layer disposed on the substrate, as
depicted in FIG. 4B. The adhesion layer 420 forms a relatively
uniform layer of material on the planar upper surface 404 of the
dielectric layer 410, the sidewalls 422 of the feature 408, and the
bottom surface 424 of the feature 408. In some implementations, the
adhesion layer 420 contains a metal or a metal nitride material,
such as titanium, titanium nitride, alloys thereof, or combinations
thereof. Exemplary materials for the adhesion layer 420 include
Tantalum (Ta), Tungsten Nitride (WN), Titanium Nitride (TiN),
TiN.sub.xSi.sub.y, Tantalum Nitride (TaN.sub.x), Silicon Nitride
(SiN), Tungsten (W), CoWP, NiMoP, NiMoB, Ruthenium (Ru), RuO.sub.2,
Molybdenum (Mo), Mo.sub.xN.sub.y, where x and y are non-zero
numbers, and combinations thereof. Adhesion layer 420 may have a
thickness within a range from about 2 .ANG. to about 100 .ANG.,
more narrowly within a range from about 3 .ANG. to about 80 .ANG.,
more narrowly within a range from about 4 .ANG. to about 50 .ANG.,
more narrowly within a range from about 5 .ANG. to about 25 .ANG.,
more narrowly within a range from about 5 .ANG. to about 20 .ANG.,
more narrowly within a range from about 5 .ANG. to about 15 .ANG.,
and more narrowly within a range from about 5 .ANG. to about 10
.ANG.. Adhesion layer 420 is generally deposited by chemical vapor
deposition (CVD), atomic layer deposition (ALD) or physical vapor
deposition (PVD) processes.
In block 320 of process 300, a nucleation layer 430 of desired
thickness is deposited on adhesion layer 420, as depicted in FIG.
40. The nucleation layer 430 may be a thin layer of tungsten which
acts as a growth site for subsequent film. The nucleation layer 430
may be deposited by techniques such as atomic layer deposition
(ALD), conventional chemical vapor deposition (CVD), or pulsed
chemical vapor deposition (CVD). This process may be performed in a
CVD processing chamber similar to that described above with
reference to FIG. 2. The nucleation layer may be deposited in the
same processing chamber used for the barrier layer soak process.
The nucleation layer 430 may comprise tungsten, tungsten alloys,
tungsten-containing materials (e.g., tungsten boride or tungsten
silicide), and combinations thereof. The nucleation layer 430 may
be deposited to a thickness in a range of about 10 angstroms to
about 200 angstroms, or about 50 angstroms to about 150 angstroms.
The nucleation layer may be deposited by flowing a tungsten
containing gas (e.g., a tungsten halide compound such as WF.sub.6)
and a hydrogen containing gas (e.g., H.sub.2, B.sub.2H.sub.6, or
SiH.sub.4) into a processing chamber, such as processing chamber
200 shown in FIG. 2. Processes for depositing a tungsten nucleation
layer are further described in commonly assigned U.S. Pat. No.
7,405,158.
In block 330 of process 300, a first tungsten film 440 of a bulk
tungsten layer 460 is deposited over the nucleation layer 430, as
depicted in FIG. 4D. As depicted in FIG. 4D, the growth of the
first tungsten film 440 along the sidewalls 422 of the feature 408
tends to close off the opening 442 of the feature before the lower
portion of the feature 408 has completely grown from the bottom
surface 424 of the feature 408 resulting in a void 444 forming
within the feature 408.
In one implementation, the first tungsten film 440 may be deposited
on or over nucleation layer 430. The first tungsten film 440 is
generally formed over by thermal CVD, pulsed-CVD, PE-CVD, or pulsed
PE-CVD. The processing chamber used to deposit the first tungsten
film 440 may be processing chamber 200. The first tungsten film 440
may contain metallic tungsten, tungsten alloys, tungsten-containing
materials (e.g., tungsten boride, tungsten silicide, or tungsten
phosphide), or combinations thereof.
In one example, the first tungsten film 440 may be deposited on or
over nucleation layer 430 on workpiece 400 which is simultaneously
exposed to a tungsten containing gas (e.g., tungsten hexafluoride
(WF.sub.6)) and a hydrogen containing gas (e.g., hydrogen
(H.sub.2)) during a CVD process. Exemplary processes for soaking
nucleation layer 430 and depositing the first tungsten film 440
thereon are further described in the commonly assigned U.S. Pat.
No. 6,156,382.
The first tungsten film 440 may be deposited using the same
processing gases, tungsten containing gas and hydrogen containing
gases as were used to deposit the nucleation layer 430. The first
tungsten film 440 may be formed in the same processing chamber as
the nucleation layer 430, such as processing chamber 200.
In one implementation, following deposition of the nucleation layer
430 and any subsequent purging or post soak processes, the
substrate may be positioned in a 300 mm processing chamber having a
volume of about 13,560 cm.sup.3 and on a pedestal having a
temperature in the range of about 100 C..degree. to about
600.degree. C. (e.g., in the range of about 300.degree. C. to
430.degree. C.). In one example, the temperature may be about
400.degree. C. Deposition of the first tungsten film 440 may be
performed with the processing chamber at a pressure in the range of
about 10 Torr to about 300 Torr (e.g., in the range of about 30
Torr to about 100 Torr). In one example, the pressure may be about
90 Torr. The reducing gas, for example, a hydrogen containing gas
such as hydrogen gas (H.sub.2), may be introduced at a continuous
flow rate between 1,000 sccm and about 8,000 sccm, such as 5,000
sccm. The reducing gas can be introduced with a carrier gas, such
as argon (Ar), at a flow rate in the range of about 0 sccm to about
20,000 sccm. In one example, argon may be introduced at a total
flow rate of 11,000 sccm. A second flow of argon may be flowed
through a purge guide (not shown in FIG. 2) at a rate from about 0
sccm to 2,000 sccm to prevent deposition gases from contacting the
edge and backside of the substrate. In one example, the argon edge
purge flow may be 500 sccm. Similarly, a second flow of hydrogen
gas (H.sub.2) may be flowed through a purge guide (not shown in
FIG. 2) at a rate from about 0 sccm to 6,000 sccm. In one example,
the hydrogen gas edge purge flow may be 2,500 sccm. In another
implementation, an additional flow of carrier gas, such as argon,
may be introduced as a bottom purge in order to prevent deposition
on the backside of the chamber heating elements. In one example,
the argon bottom purge flow may be 5,000 sccm. The
tungsten-containing compound may be tungsten hexafluoride
(WF.sub.6) and may be introduced at a continuous flow rate in the
range of about 50 sccm to 500 sccm, such as in the range of about
300 sccm to 400 sccm.
The first tungsten film 440 may be deposited at a deposition rate
from about 100 .ANG./minute and about 1,200 .ANG./minute, for
example, from about 500 .ANG./minute and about 800 .ANG./minute.
The first tungsten film 440 may have a thickness within a range
from about 10 .ANG. to about 200 .ANG., and more narrowly within a
range from about 20 .ANG. to about 100 .ANG..
In block 340 of process 300, the first tungsten film 440 of the
bulk tungsten layer 460 is etched using the tungsten containing gas
to remove a portion of the first tungsten film 440, as depicted in
FIGS. 4D and 4E. The etching process (also referred to as an
etchback process) removes a portion of the first tungsten film 440
from along the sidewalls 422 of the feature 408 to clear a portion
of the feature opening 442 for further deposition of tungsten
material. The etching process may also be performed in the same
processing chamber, such as processing chamber 200, as the tungsten
deposition process of block 330. The etching process is generally
performed using the same tungsten containing gases as used in block
330.
In one implementation, following deposition of the first tungsten
film 440 and any subsequent purging or post soak processes, the
first tungsten film 440 is etched using a plasma etching process.
The plasma may be formed by coupling RF power to a treatment gas
such as He, Ar, O.sub.2, N.sub.2, or combinations thereof. The
plasma may be formed by a remote plasma source (RPS) and delivered
to the processing chamber.
During the etch process, the pedestal may have a temperature in the
range of about 100 C..degree. to about 600.degree. C. (e.g., in the
range of about 300.degree. C. to 430.degree. C.). In one example,
the temperature may be about 400.degree. C. Etching of the first
tungsten film 440 may be performed with the processing chamber at a
pressure in the range of about 0.1 Torr to about 5 Torr (e.g., in
the range of about 0.5 Torr to about 2 Torr). In one example, the
pressure may be about 1 Torr. The treatment gas (e.g., argon (Ar))
may be introduced at a flow rate in the range of about 100 scorn to
about 3,000 sccm. In one example, argon may be introduced at a
total flow rate of 2,000 sccm. A second flow of argon may be flowed
through a purge guide (not shown in FIG. 2) at a rate from about 0
sccm to 2,000 sccm to prevent deposition gases from contacting the
edge and backside of the substrate. In one example, the argon edge
purge flow may be 500 sccm. Similarly, a second flow of hydrogen
gas (H.sub.2) may be flowed through a purge guide (not shown in
FIG. 2) at a rate from about 0 sccm to 6,000 sccm. In one example,
the hydrogen gas edge purge flow may be 2,500 sccm. In another
implementation, an additional flow of treatment gas, such as argon,
may be introduced as a bottom purge in order to prevent deposition
on the backside of the chamber heating elements. In one example,
the argon bottom purge flow may be 5,000 sccm. The
tungsten-containing compound may be tungsten hexafluoride
(WF.sub.6) and may be introduced at a continuous flow rate in the
range of about 1 sccm to 150 sccm, such as in the range of about 3
sccm to 100 sccm.
The arrows 464' represent the direction of atomic fluorine during
the etch process causes the atomic fluorine to collide with the top
(planar) surface of the first tungsten film 440.
In implementations where the plasma is formed by coupling RF power
to the treatment gas, an RF power between 50 W and 100 W, such as
75 W at an RF power frequency from about 10 MHz to about 30 MHZ,
for example, about 13.56 MHz, may be used.
In implementations where the plasma is formed in a remote plasma
source (RPS) the power application may be from about 1,000 Watts to
about 6,000 Watts, for example, from about 1,000 Watts to about
2,000 Watts, with a treatment gas flow rate (e.g., argon) from
about 500 sccm to about 6,000 sccm.
Portions of the first tungsten film 440 may be removed at an etch
rate from about 0.1 .ANG./second to about 10 .ANG./second, for
example, from about 0.5 .ANG./second to about 3 .ANG./second. The
processing conditions for the etchback process are typically
selected such that the overhang portion 443 of the first tungsten
film 440 is removed from the first tungsten film 440.
In block 350 of process 300, a second tungsten film 448 of the bulk
tungsten layer 460 is deposited over the remaining first tungsten
film 446 after etching of the first tungsten film 440, as depicted
in FIG. 4F. The second tungsten film 448 of the bulk tungsten layer
460 may be deposited in the same processing chamber as the
deposition process of block 330 and the etching process of block
340, such as processing chamber 200. The second tungsten film 448
of the bulk tungsten layer 460 may be deposited using the same
tungsten containing gases as used in block 330 and block 340.
In one implementation, following etching of the first tungsten film
440, deposition of a second tungsten film 448 of the bulk tungsten
layer 460 is performed. The second tungsten film 448 of the bulk
tungsten layer 460 may be performed on a pedestal having a
temperature in the range of about 100 C..degree. to about
600.degree. C. (e.g., in the range of about 300.degree. C. to about
430.degree. C.). In one example, the temperature may be about
400.degree. C. Deposition of the second tungsten film 448 of the
bulk tungsten layer 460 may be performed with the processing
chamber at a pressure in the range of about 10 Torr to about 300
Torr (e.g., in the range of about 30 Torr to about 100 Torr). In
one example, the pressure may be about 90 Torr. The reducing gas,
for example, hydrogen gas (H.sub.2), may be introduced at a
continuous flow rate between 1,000 sccm and about 8,000 sccm, such
as 5,000 sccm. The reducing gas can be introduced with a carrier
gas, such as argon (Ar), at a flow rate in the range of about 0
sccm to about 20,000 sccm. In one example, argon may be introduced
at a total flow rate of 11,000 sccm. A second flow of argon may be
flowed through a purge guide (not shown in FIG. 2) at a rate from
about 0 sccm to 2,000 sccm to prevent deposition gases from
contacting the edge and backside of the substrate. In one example,
the argon edge purge flow may be 500 sccm. Similarly, a second flow
of hydrogen gas (H.sub.2) may be flowed through a purge guide (not
shown in FIG. 2) at a rate from about 0 sccm to 6,000 sccm. In one
example, the hydrogen gas edge purge flow may be 2,500 sccm. In
another implementation, an additional flow of carrier gas, such as
argon, may be introduced as a bottom purge in order to prevent
deposition on the backside of the chamber heating elements. In one
example, the argon bottom purge flow may be 5,000 sccm. The
tungsten-containing compound may be tungsten hexafluoride
(WF.sub.6) and may be introduced at a continuous flow rate in the
range of about 50 sccm to 500 sccm, such as in the range of about
300 sccm to 400 sccm.
The second tungsten film 448 of the bulk tungsten first tungsten
layer 440 may be deposited at a deposition rate from about 1,200
.ANG./minute and about 3,000 .ANG./minute. The second tungsten film
448 of the bulk tungsten first tungsten layer 440 may be deposited
at a deposition rate from about 1,800 .ANG./minute and about 2,300
.ANG./minute.
In block 360 of process 300 it is determined whether the overall
desired thickness of the bulk tungsten layer 460 has been achieved.
If the desired thickness of bulk tungsten layer 460 has been
achieved, the process 300 ends. If the desired thickness of the
bulk tungsten layer 460 has not been achieved any of the
aforementioned deposition and etching processes may be performed
again. The determination of the thickness of the of the tungsten
bulk layer may be performed using conventional processes such as,
for example, spectroscopic measurements.
Process Integration
A tungsten-containing layer and barrier layer as described above
has shown particular utility when integrated with traditional
nucleation fill techniques to form features with excellent film
properties. An integration scheme can include ALD, CVD, pulsed-CVD
processes, plasma-enhanced CVD, or pulsed PE-CVD, to deposit
tungsten-containing layers and barrier layers while a nucleation
layer may be deposited by ALD process. Integrated processing
systems capable of performing such an integration scheme include
ENDURA.RTM., ENDURA SL.RTM., CENTURA.RTM., or PRODUCER.RTM.
processing systems, each available from Applied Materials, Inc.,
located in Santa Clara, Calif. Any of these systems may be
configured to include at least one ALD chamber for depositing the
tungsten-containing layer and barrier layer, at least one ALD or
pulsed-CVD chamber for depositing the nucleation layer, at least
one CVD chamber for depositing bulk fill, and/or at least one PVD
chamber for additional materials. In one implementation, one ALD or
CVD chamber may be configured to perform all vapor deposition
processes related to the tungsten-containing layers.
FIG. 5 is a schematic plan view of a cluster tool 500 that may be
used for performing the implementations described herein. A similar
multi-chamber processing system is disclosed in commonly assigned
U.S. Pat. No. 5,186,718. Processing system 500 generally includes
load lock chambers 502 and 504 for the transfer of substrates into
and out from processing system 500. Typically, since processing
system 500 is under vacuum, load lock chambers 502 and 504 may
"pump down" the substrates introduced into processing system 500.
First robot 510 may transfer the substrates between load lock
chambers 502 and 504, and a first set of one or more substrate
processing chambers 512, 514, 516, and 518 (four are shown). Each
processing chamber 512, 514, 516, and 518, may be outfitted to
perform a number of substrate processing operations such as ALD,
CVD, PVD, etch, pre-clean, de-gas, orientation, or other substrate
processes. First robot 510 also transfers substrates to/from one or
more transfer chambers 522 and 524.
Transfer chambers 522 and 524 are used to maintain ultra-high
vacuum conditions while allowing substrates to be transferred
within processing system 500. Second robot 530 may transfer the
substrates between transfer chambers 522 and 524 and a second set
of one or more processing chambers 532, 534, 536, and 538. Similar
to processing chambers 512, 514, 516, and 518, processing chambers
532, 534, 536, and 538 may be outfitted to perform a variety of
substrate processing operations, such as ALD, CVD, PVD, etch,
pre-clean, de-gas, or orientation. Any of processing chambers 512,
514, 516, 518, 532, 534, 536, and 538 may be removed from
processing system 500 if not necessary for a particular process to
be performed by processing system 500. Microprocessor controller
520 may be used to operate all aspects of processing system
500.
In one arrangement, each processing chamber 532 and 538 may be an
ALD chamber or other vapor deposition chamber adapted to deposit
sequential layers containing different chemical compound. For
example, the sequential layers may include a layer, a barrier
layer, and a nucleation layer. Processing chambers 534 and 536 may
be an ALD chamber, a CVD chamber, or a PVD adapted to form a bulk
layer. Processing chambers 512 and 514 may be a PVD chamber, a CVD
chamber, or an ALD chamber adapted to deposit a dielectric layer.
Also, processing chambers 516 and 518 may be an etch chamber
outfitted to etch features or openings for interconnect features.
This one particular arrangement of processing system 500 is
provided to illustrate some implementations of the disclosure and
should not be used to limit the scope of other implementations of
the disclosure.
In another integration scheme, one or more ALD chambers are
integrated onto a first processing system while one or more bulk
layer deposition chambers are integrated onto a second processing
system. In this configuration, substrates are first processed in
the first system where a layer, a barrier layer and a nucleation
layer is deposited on a substrate sequentially. Thereafter, the
substrates are moved to the second processing system where bulk
deposition occurs.
In yet another integrated system, a system may include nucleation
deposition as well as bulk fill deposition in a single chamber. A
chamber configured to operate in both an ALD mode as well as a
conventional CVD mode may be used in processes described herein.
One example of such a chamber is described in commonly assigned
U.S. Pat. No. 6,878,206.
In certain implementations using the deposition-etch-deposition
process with WF.sub.5 described herein, seamless gap-fill was
achieved with a single chamber solution.
While the foregoing is directed to implementations of the present
disclosure, other and further implementations of the disclosure may
be devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
* * * * *